Circumferential electroslag welding

ABSTRACT

Circumferential electroslag welding for jointing a pair of cylindrical members in which a water-cooled mold to be removed after the start of welding is placed outside of the annular space formed between the members so that the deposit metal at the start zone is formed outside of the annular space and the tip of a welding wire is steadily guided through a consumable nozzle, the top end of which is electrically connected to the tip of a nonconsumable nozzle in the start zone, said top end being partially cut off so that the consumable nozzle can be detached from said wire when said consumable nozzle is consumed to the point of the cut.

United States Patent [191 Wada et al. 1 May 22, 1973 CIRCUMFERENTIALELECTROSLAG WELDING Primary Examiner-J. V. Truhe Assistant Examiner-L.A. Schutzman [75] Inventors: Takeshi Wada; Hisanao Kita;

Michio Kitamura, all of Hitachi-shi, Atmmey Cra'g Antonelh & Hm J apan57 ABSTRACT 73 Assi e: Hita hi Ltd. T k ,1 l 1 gne c 0 yo apanCircumferential electroslag welding for jointing a pair Flledi 1971 ofcylindrical members in which a water-cooled mold [211 APPL NOJ 190,588to be removed after the start of welding is placed outside of theannular space formed between the members so that the deposit metal atthe start zone is [52] U.S. Cl ..219/73, 219/60 A, 219/137 f d Outside fthe annular Space and the tip of a [51] Int. Cl. ..B23k 9/ 18 weldingwire is steadily guided through a consumable [58] Field Of Search..2l9/73, 74, 76, 137, nozzle, the top end of which is electricallyconnected 219/6OA to the tip of a non-consumable nozzle in the startzone, said top end being partially cut ofi so that the [56] ReferencesC'ted consumable nozzle can be detached from said wire UNITED STATESPATENTS wfhtelp 83k: consumable nozzle is consumed to the point 0 e cu3,433,926 3/1969 Dick ..2l9/137 3,21 1,887 10/1965 Cotterman ..2l9/ 1263 Claims, 10 Drawing Figures PATENTEB MY 2 2 I975 FIG. 20 FIG. 2b PRIORART P RIOR ART INVENTORS TA KESHI WADAHI5ANAO KITA,

MI HIO KITAM URA 1 CIRCUMFERENTIAL ELECTROSLAG WELDING DESCRIPTION OFTHE INVENTION The present invention relates to improvements incircumferential electroslag welding and, more particularly, to animprovement in the start of welding for circumferential welding ofcylindrical members, whereby the start operation can be successfullyperformed and a change of the start operation to the steady operationcan be carried out smoothly.

In the known methods for circumferential electroslag welding, a pair ofcylinders to be welded are axially spaced apart by a predetermineddistance to form an annular space therebetween. Wire is guided throughnon-consumable nozzles to a welding zone which is formed by awater-cooled partition shoe inserted in the annular space between thecylinders. The start zone in the conventional methods is located in theannular space and, therefore, since the weld metal of the start zone isunsatisfactory, in order to accomplish a satisfactory meeting of thestart and finish zones a chipping op eration followed by the step ofgrinding the chipped surface must be carried out. Since it is verydifficult to handle and manipulate tools or devices, such as grinders orchippers, within the narrow annular space, particularly in the case ofthick cylinders, these operations necessarily are quite difficult andrequire a very long period of time.

In the conventional methods, the machining of the start zone cannot beperformed until after the welding is stopped. This stopping of weldingloses almost all of the advantages of electroslag welding which has beenreferred to as the most important and productive new method among recentmethods of automatic welding. The melting of the start and finish zonesis inherent in circumferential electroslag welding and, therefore, it isvery important to solve the problems relating to the necessary machiningof the start zone in order to improve the productivity ofcircumferential electroslag welding.

SUMMARY OF THE INVENTION It is, therefore, an object of the presentinvention to improve the work efficiency of circumferential electroslagwelding. I

It is another object of the present invention to improve the startoperation of circumferential electroslag welding. I

It is still another object of the present invention to provide animproved method of circumferential electroslag welding in which thechange from the start operation to the steady operation can be carriedout easily and smoothly.

The present invention provides a start operation for circumferentialelectroslag welding in which a watercooled start shoe for defining astart zone is placed outside of the annular space formed between a pairof cylindrical members to be welded and a consumable nozzle iselectrically connected to a tip portion of a nonconsumable nozzle, whichcan be detached from the non-consumable nozzle when it is desired tointerchange the start operation for a steady operation.

Other objects, features and advantages of the present invention will beapparent from the following detailed description when taken inconjunction with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is an end sectional view of astandard circumferential electroslag welding apparatus;

FIGS. 2a and 2b are detail views of conventional circumferentialelectroslag welding arrangements;

FIG. 3a to 30 are detail views of a circumferential electroslag weldingarrangement according to the present invention;

FIGS. 4 and S are perspective views of consumable nozzles according tothe present invention;

FIG. 6 is a perspective view of a start shoe mounted on the innercircumference of a pair of cylinders; and

FIG. 7 is a perspective view of a partition shoe inserted into a groove.

DETAILED DESCRIPTION OF THE INVENTION As well known, a pair ofcylindrical members 1 to be welded by their ends are spaced axiallyapart by a predetermined distance to form an annular space therebetween.They are mounted on a pair of turning rollers 4 such that they areturned in the welding direction in accordance with the necessary advanceof the welding point.

A plurality of non-consumable nozzles 7, whose number is determined inaccordance with the thickness of the cylinders or other conditions, aresupported by a column 2 which is provided with wire supply means 3. Wire9 is supplied to each of the non-consumable nozzles and guided to awelding zone which is defined by an inner circumferential shoe 8 and anouter circumferential shoe 6. The shoes are supported by suitable means,such as a supporter 5.

In accordance with 'a conventional start method, the start zone of thewelding is confined by an inner circumferential shoe 11 and a partitionshoe 12 inserted into the annular space 10 between the cylinders 1, asshown in FIGS. 2a and 2b. The wire 9 to be used at the start of weldingis fed off from a reel and, therefore, the

portion of wire projecting from the non-consumable nozzle 7 tends tocurl so that it is difficult to steadily guide the tip of wire to thestart zone. This is the reason why the length of the projecting portionof wire is limited in the conventional method. Since the start zone,which includes welding defects, is placed inside of the annular space,the weld metal 13 at the start zone must be removed by suitablemachining, such as, chipping and grinding, along the line A, prior tojoining the start zone and finish zone. Because the annular space 10 isnot wide, in general, in view of the work efficiency, the machining isnot easy and therefore takes a very long period of time.

In order to solve the above problem, an attempt was made to accomplish aproductive machining prior to the meeting of the start zone and finishzone. In accordance with the present invention, the start zone ofwelding is placed outside of the annular space as will be explainedbelow. In order to perform the abovementioned process, the presentinvention also provides new water-cooled shoes as shown in FIGS. 3a to30 and FIGS. 6 and 7. A water-cooled shoe 20 having a hollow 27 isprovided at the inner circumference of the cylinder and a rod-shapedshoe 21, which is water-cooled, is inserted into the annular space todefine a start zone with the inner circumferential shoe 20. If a startzone is formed outside the groove, the welding operation can be carriedout with high work efficiency since there is no difficult machining tobe carried out within the narrow annular space. The weld metal 28 at thestart zone can be removed easily without affecting the performance ofthe welding.

The present inventors, however, discovered that it was substantiallyimpossible to steadily guide the tip of the wire to the start zone, aslong as the wire is guided through a non-consumable nozzle 7. Theinventors have experienced a number of faults in the start operation.One of the most important causes of fault lies in the fact that thedepth or distance between the top of the non-consumable nozzle and thebottom or start zone of the inner circumferential shoe 20 is too largeto steadily guide the wire 9 to the start zone.

In order to steadily guide the wire, the present invention proposes thatthe wire be guided through a consumable nozzle 30 supported on thelarger support member 18. In this embodiment, the support member 18 isdetachably fixed by fixing members 19 to the nonconsumable nozzle 7. Tothe tip 23 of the support member 18 is fixed, by means of welding, forexample, a consumable nozzle 30, the top end of which is partially cutoff to form a cut-out portion 24. The consumable nozzle 30 can beremoved from the nonconsumable nozzle 7 when the consumable nozzle 30 isconsumed up to the cut 24, as shown in FIG. 30. The wire 9 is suppliedthrough the non-consumable nozzle 7 and the consumable nozzle 30 to thestart zone.

The tip of wire 9 can be steadily guided through the consumable nozzle30 to the start zone without any trouble and, therefore, the fault whichoften occurs during the start can be eliminated.

When the consumable nozzle 30 is consumed up to the cut 24 during theprogress of the welding, the top end of the nozzle 30, which isconnected to the support member 18, is detached from the non-consumablenozzle 7, whereby the steady welding operation can be smoothly carriedout. In FIGS. 3a to 30, numeral 28 designates weld metal or depositmetal, 26 molten metal and 25 electroconductive flux. After interchangeof welding using the consumable nozzle to steady welding using thenon-consumable nozzle is finished, and at the same time, the consumablenozzle is detached from the non-consumable nozzle along with the supportmember. The steady welding is then carried on using an innercircumferential shoe 22 and outer circumferential shoe 6 to deposit theweld metal 29. The weld metal at the start zone 28 can be easilymachined and removed along the line B during welding or after finish ofcircumferential welding. In FIG. 30 the shoes 20 and 21 are removed.

In order to detach the support member 18 and consumable nozzle 30 fromthe non-consumable nozzle 7, the top end of the nozzle 30 is cut off asshown in FIG.

4. The present inventors have experienced the trouble that wire 9deflects from the cut 24 formed at the top end of the consumable noule30 when the length of the cut is made sufficiently large'to ensure anadequate distance between the surface of molten slag and the tip of thenon-consumable nozzle. The consumable nozzle shown in FIG. 5 has anextended slit 3], whereby the deflection or run-out of wire from theconsumable nozzle 30 is prevented by the upwardly extended portion. Byemploying this consumable nozzle, the run-out of wire can be preventedwithout losing detachability of the consumable nozzle.

The inner shoe 20 used in the start zone has a contour as shown in FIG.6 in which the water-cooling conduits 32 are fixed to the outer facethereof and plates 34 are in contact with the inner face of cylinders tobe welded.

The shoe 21 to be inserted into the annular space to form the start zonewith the inner circumferential shoe 20 has a contour as shown in FIG. 7,with which a water-cooling means 33 is provided in connection with aninternal conduit in the shoe 21.

What is claimed is:

1. In an apparatus for circumferential electroslag welding of a pair ofcylindrical members which are axially spaced apart to form an annularspace therebetween, a welding arrangement comprising a watercooledhollow shoe having the form of a pocket and being mounted on an innersurface of said cylindrical members adjoining said annular space, awater-cooled rod-shaped shoe inserted into said annular space againstthe bottom of said hollow shoe so that a start zone is formed out of theannular space, a nozzle inserted into said annular space and feedingmeans for feeding wire through said nozzle into said start zone, said,nozzle comprising a first non-consumable portion and a second consumableportion electroconductively and detachably mounted on saidnon-consumable portion and providing an end through which said wireprotrudes into said start zone, said consumable nozzle portion includingmeans having a longitudinal portion thereof removed in such a mannerthat the consumable noule is detached when it has been consumed to thepoint of the removed longitudinal portion.

2. The combination defined in claim 1 wherein said hollow shoe has anopening which is approximately as wide as said annular space and isdisposed in alignment therewith.

3. The combination defined in claim 1 wherein said consumable nozzle hasat least one extended slit extending longitudinally from said removedlongitudinal portion.

1. In an apparatus for circumferential electroslag welding of a pair ofcylindrical members which are axially spaced apart to form an annularspace therebetween, a welding arrangement comprising a water-cooledhollow shoe having the form of a pocket and being mounted on an innersurface of said cylindrical members adjoining said annular space, awater-cooled rod-shaped shoe inserted into said annular space againstthe bottom of said hollow shoe so thaT a start zone is formed out of theannular space, a nozzle inserted into said annular space and feedingmeans for feeding wire through said nozzle into said start zone, saidnozzle comprising a first non-consumable portion and a second consumableportion electroconductively and detachably mounted on saidnon-consumable portion and providing an end through which said wireprotrudes into said start zone, said consumable nozzle portion includingmeans having a longitudinal portion thereof removed in such a mannerthat the consumable nozzle is detached when it has been consumed to thepoint of the removed longitudinal portion.
 2. The combination defined inclaim 1 wherein said hollow shoe has an opening which is approximatelyas wide as said annular space and is disposed in alignment therewith. 3.The combination defined in claim 1 wherein said consumable nozzle has atleast one extended slit extending longitudinally from said removedlongitudinal portion.